It is well known that substantial pain and resultant inconvenience is associated with a range of conditions, such as headaches (in particular, migraine and severe repetitive chronic headaches), temperomandibular joint pain dysfunction, whiplash and other neck complaints, repetitive strain injury and other arm, wrist and hand muscle complaints, chronic back pain, various eye complaints (e.g. diplopia, astigmatism, photophobia, lazy eye), dyslexia and various ear complaints, from which all members of the community suffer to varying degrees. Whilst there is a wide range of treatments for the relief of the pain associated with the conditions such treatments are of variable effectiveness and in many situations do not relieve entirely the pain or prevent the recurrence of the conditions.
The object of the present invention is to alleviate the pain caused by the above conditions and to minimize the likelihood of recurrence of the conditions.
According to the present invention there is provided a method of treating muscle imbalance comprising, unlocking the interdigitation of the teeth of the upper and lower jaws to allow the muscles supporting the jaws to function correctly and thereby to move the lower jaw in a preferred path during mastication, as described herein.
The term "preferred path during mastication" as used herein is understood to mean generally horizontal circular movement of the lower jaw with respect to the upper jaw without interference of the teeth.
It is preferred that the interdigitation of the teeth is unlocked by positioning a splint over at least the molar teeth of the lower jaw, the splint having a contact surface for at least the molar teeth of the upper jaw which prevents direct contact between the molar teeth of the upper and lower jaws and repositions the molar teeth of the lower jaw with respect to the upper jaw to permit movement of the lower jaw in the preferred path.
In a preferred arrangement the method comprises adjusting the contact surface periodically to increase the spacing between the molar teeth in the upper and lower jaws thereby to allow the muscles supporting the lower jaw to relax and function at their correct length and tone.
According to the present invention there is also provided a splint for the lower jaw of a patient, said splint comprising a contact surface for at least the molar teeth of the upper jaw for preventing interlocking interdigitation of the molar teeth thereby to allow the muscles supporting the jaws to move the lower jaw in a preferred path, as described herein.
In a preferred arrangement the thickness of the splint is selected to separate the molar teeth of the upper and lower jaws by a sufficient distance to allow the muscles supporting the jaws to function optimally, thereby relieving any build up of stress in the muscles.
It is preferred that the contact surface is formed so that there is point contact between each molar tooth of the upper jaw and the contact surface. It is particularly preferred that the point contact is between the lingual cusps of each molar tooth of the upper jaw and the contact surface.
It is preferred that the contact surface is formed so that when the molar teeth of the upper jaw contact the splint, the molar teeth are inclined outwardly and downwardly in the range of 15.degree. to 25.degree. measured with respect to a vertical axis. It is particularly preferred that the angle of inclination is 20.degree..
It is preferred that the splint comprises two arms and a bridge interconnecting the arms, and that the arms are formed to overlie the molar teeth on respective sides of the lower jaw. In a particularly preferred arrangement the arms extend rearwardly from the second premolars and do not overlie the first premolars and the incisors. Preferably each arm is generally U-shaped in transverse section with a dome shaped central section separating two sides.
According to the present invention there is also provided a method of treating muscle imbalance comprising:
(a) modifying the orientation of the jaws of a patient with respect to each other, and
(b) adjusting the separation of molar teeth of the lower jaw and the upper jaw when the jaws are in a closed position.
The present invention is based on the realization that the pain associated with many conditions is caused by a muscle imbalance that can be traced to the masticatory muscles controlling the lower jaw. The conditions include headaches (in particular migraine and severe repetitive chronic headaches), temperomandibular joint pain dysfunction, whiplash and other neck complaints, repetitive strain injury and other arm, wrist and hand muscle complaints, chronic back pain, various eye complaints (e.g. diplopia, astigmatism, photophobia, lazy eye) and various ear complaints.
The muscle imbalance is caused by a number of factors. However, it is believed that the principal factor is a particular type of interdigitation of the molar teeth which interferes with the normal masticatory movement of the teeth, i.e. generally circular horizontal movement of the lower jaw with the molar teeth of the upper and lower jaws in contact. In extreme cases the interdigitation restricts the movement of the mandible to movement up and down vertically during mastication which in turn causes abnormal functioning of the masticatory muscles. One consequence of the abnormal functioning is that the balance of the muscles is disturbed and this leads to muscle spasm, pain and dysfunction, all of which can be traced by the patient to the general region in the body in which the muscles are located.
Furthermore, the imbalance in the masticatory muscles is transferred to muscles which are connected directly to or are associated with the masticatory muscles. Similarly, the imbalance in these muscles leads to muscle spasm, pain and dysfunction, all of which are experienced by the patient in the region of the body in which the muscles are located. For example, an imbalance in the Masseter muscle, one of the masticatory muscles, may lead to the patient experiencing pain in the facial region. The muscular connections and associations are sufficiently extensive that any imbalance in the masticatory muscles may be transferred extensively throughout the body to regions such as the neck, shoulder, lower back, arms and legs.
In many situations, the imbalance in the masticatory muscles and muscles connected directly to or associated with the masticatory muscles is such that the pain is at a tolerable level and is not regarded by the patient as being of an abnormal nature requiring treatment. In such situations an external event such as a motor car accident or an overworking of imbalanced muscles may aggravate the imbalance to the extent that the pain exceeds the tolerable level.
For example, in the case of motor car accidents in which a person experiences whiplash, the hyperflexion of the muscles in the neck region increases the imbalance of the muscles in the region to the extent that the patient experiences considerable pain. The treatment of the pain as a symptom of whiplash may alleviate the pain to a certain extent, but in many instances does not correct the imbalance in the muscles to the previous tolerable level, in which case the patient continues to report pain. As a consequence, the whiplash injury is considered to be far more serious than would be expected in view of the particular circumstances of the motor car accident. In other words, the motor car accident tends to direct the clinician away from the actual cause of the pain, namely the pre-existing imbalance in the muscles.
Another example relates to overworking of muscles in the arm due to carrying out repetitive manual functions. If the muscles in the arm are unbalanced, due to the transference of an imbalance in the masticatory muscles, the repetitive working of the muscles in the arm may aggravate the imbalance to the extent that pain above a previously tolerable level is experienced by the patient. Given the absence of a history of pain in the muscles of the arm the logical conclusion is that the injury is due to the repetitive manual functions and the injury is classified as a repetitive strain injury with treatment selected accordingly. Such a diagnosis overlooks the fact that if the muscles were not unbalanced then the muscles might have been able to cope with the manual work considered to be the cause of the repetitive strain injury.
In both examples noted above, the treatment of the cause of the initial imbalance, i.e. treatment of the imbalance in the masticatory muscles, has the effect of allowing the other muscles to which the imbalance is transferred to work in the normal manner with the result that the external influence such as the motor car accident or the excessive working of the muscles in the arm does not result in the extreme symptoms that characterize many injuries considered to be attributable to the external influences.